U.S. Pat. No. 6,532,912 B2 relates to piston cooling for internal combustion engines having a crankshaft, a plurality of pistons and a crankcase. The crankcase is split up into divided regions by a plurality of partition walls, a forced-feed lubrication system being integrated in the crankcase, so that lubricant can circulate through the crankcase. In addition, the crankcase has a plurality of longitudinal bores which extend through a respective partition wall of the crankcase generally coaxially to one another and generally parallel to the crankshaft. The piston-cooling system has a plurality of bores which are each incorporated in the respective partition wall and are connected to the force-feed lubrication systems. In addition, the piston-cooling system has a plurality of spray nozzles, of which each is individually fitted in an associated longitudinal bore and is directed to spray lubricant onto an underside of the piston. The spray nozzles are connected to a respective bore and to the forced-feed lubrication system. Each spray nozzle is designed as a compact turned part and has a transverse bore with opposite open ends. The open ends are each closed with a stopper. In addition, the spray nozzle has two spray holes which are symmetrical relative to the center, the lubricant flowing through the inlet bore to pass into the closed transverse bore and sprayed out of the spray holes. The inlet bore aligns with the bore of the respective partition wall in which the spray nozzle is fitted.
U.S. Pat. No. 4,010,718 discloses a reciprocating internal combustion engine having a cylinder block containing at least one cylinder, at least one piston reciprocating in the associated cylinder, a crankcase, a crankshaft rotatably mounted in the crankcase in at least one bearing, and at least one connecting rod for connecting the crankshaft to the associated pistons. The crankcase is provided with a lubricating-oil passage. The crankcase has a bore in each case between a main bearing and the associated piston, this bore being connected to the lubricating-oil passage. A tubular nozzle assembly is firmly fitted into the bore of the crankcase in a precisely predetermined position. The nozzle assembly has an inner cavity which is connected to the lubricating-oil passage. In addition, the lubricating-oil assembly has at least one nozzle passage which has been formed on the nozzle assembly in a precisely predetermined position before the nozzle assembly is fitted into the associated bore.
U.S. Pat. No. 5,533,472 relates to an oil-jet-nozzle piston-cooling arrangement for an internal combustion engine having two adjacent cylinders, in which reciprocating pistons are mounted. A crankshaft space is arranged between the cylinders, a crankshaft being arranged with at least one lubricating bearing in the crankshaft space. The cylinder block has journals between the adjacent cylinders to carry the crankshaft bearing. An oil feed passage is incorporated in the cylinder block to direct lubricating oil to the journal and to the bearing. A groove is incorporated in the cylinder block, at least one section of the groove being connected to the crankshaft journal to obtain lubricating oil from the feed line. A first passage is incorporated in the cylinder block, this first passage extending between the adjacent cylinders essentially parallel to the crankshaft and being arranged above the crankshaft journal. A second passage is incorporated in the cylinder block, this second passage extending between the groove and the first passage. The oil-spray-nozzle piston-cooling system has a spray arrangement which has an inlet end and an opposite outlet end. Oil passes through the inlet end into the spray nozzle, this oil being sprayed out through the outlet end. The spray nozzle is fitted in the second passage, so that its outlet end is adjacent to the groove to obtain oil from the journal, so that its outlet end is open to the first passage to produce oil streams which spray upwards through the first passage and the cylinders against the underside of the adjacent pistons.
However, U.S. Pat. No. 5,533,472 also relates to an internal combustion engine having a cylinder block which accommodates reciprocating pistons inside a piston cylinder. A connecting rod connects the piston to a crankshaft. The cylinder block has a crankshaft receptacle under the piston and a crankshaft journal for mounting a crankshaft bearing and an oil feed line on one side of the piston cylinder. The oil feed line is connected to a groove and the crankshaft journal and also to the crankshaft bearing to provide a passage through the bearing to the crankshaft. A passage extends from the oil groove to the crankshaft receptacle and is provided with an oil-spray nozzle which sprays oil onto an underside of the piston. The oil-spray nozzle has an element which is incorporated in the passage which extends from the oil groove to the crankshaft receptacle. A spray nozzle has a bottom region with outlets and a top region with inlets. A projection of the element is designed in such a way that it sits in the oil groove. The projection is of such a width that it is accommodated snugly in the oil groove.
It is known that piston oil-spray nozzles for cooling the pistons in the cylinder block are positioned below the cylinder barrels. These piston oil-spray nozzles require a pressurized oil supply, which is realized by means of a separate longitudinal bore in the cylinder block. This requires considerable design effort and additional production cost
The inventors of the present invention have recognized that a cheaper, simpler, more robust device for providing piston cooling is desired.